Manganese oxide octahedral molecular sieves: preparation, characterization, and applications

A thermally stable 3 x 3 octahedral molecular sieve corresponding to natural todorokite (OMS-1) has been synthesized by autoclaving layer-structure manganese oxides, which are prepared by reactions of MnO(4)(-) and Mn(2+) under markedly alkaline conditions. The nature and thermal stability of products depend strongly on preparation parameters, such as the MnO(4)(-)/Mn(2+) ratio, pH, aging, and autoclave conditions. The purest and the most thermally stable todorokite is obtained at a ratio of 0.30 to 0.40. Autoclave treatments at about 150 degrees to 180 degrees C for more than 2 days yield OMS-1, which is as thermally stable (500 degrees C) as natural todorokite minerals. Adsorption data give a tunnel size of 6.9 angstroms and an increase of cyclohexane or carbon tetrachloride uptake with dehydration temperature up to 500 degrees C. At 600 degrees C, the tunnel structure collapses. Both Lewis and Br?nsted acid sites have been observed in OMS-1. Particular applications of these materials include adsorption, electrochemical sensors, and oxidation catalysis.     

Templating of mesoporous molecular sieves by nonionic polyethylene oxide surfactants

Mesoporous silica molecular sieves have been prepared by the hydrolysis of tetraethylorthosilicate in the presence of low-cost, nontoxic, and biodegradable polyethylene oxide (PEO) surfactants, which act as the structure-directing (templating) agents. This nonionic, surfactant-neutral, inorganic-precursor templating pathway to mesostructures uses hydrogen bonding interactions between the hydrophilic surfaces of flexible rod- or worm-like micelles and Si(OC(2)H(5))(4-x)(OH)(x) hydrolysis products to assemble an inorganic oxide framework. Disordered channel structures with uniform diameters ranging from 2.0 to 5.8 nanometers have been obtained by varying the size and structure of the surfactant molecules. Metal-substituted silica and pure alumina mesostructures have also been prepared by the hydrolysis of the corresponding alkoxides in the presence of PEO surfactants. These results suggest that nonionic templating may provide a general pathway for the preparation of mesoporous oxides.     

Nanoscale imaging of molecular adsorption

In situ atomic force microscope observations were made of the adsorption of anions (1- or 2-) of the organic diacid 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid from aqueous solution onto the (0001) surface of hydrotalcite (HT), a layered clay. This adsorption process is believed to mimic the ion-exchange reactions that occur within the layers of HT and other layered clays. Atomic force microscope images of the (0001) surfaces of HT, acquired in aqueous solutions, reveal an ordered structure with respect to magnesium and aluminum atoms. In the presence of the anions, atomic force microscopy indicates pH-dependent adsorption onto the formally cationic HT surface. The anion coverage is governed by electroneutrality and steric interactions between the bulky anions within the adsorbed layer, whereas the orientation of the anions with respect to the HT surface is dictated by coulombic interactions and hydrogen bonding between the anion's sulfonate moiety and clay hydroxyl triads. These observations reveal that the reversible adsorption of molecular species can be examined directly by in situ atomic force microscopy, providing details of surface stoichiometry and adlayer symmetry on the local, molecular level.     

Control of granulocytes and macrophages: molecular, cellular, and clinical aspects

The production and functional activity of two important white blood cells, the granulocytes and macrophages, are regulated mainly by a group of glycoprotein colony-stimulating factors. The colony-stimulating factors have been mass-produced with recombinant technology and are now proving of value in preventing or suppressing infections in a variety of individuals with subnormal or defective formation of blood cells.     

Structural aspects of reversible molecular oxygen uptake

The system IrX(CO)[P(C(6)H(5))(3)](2) in benzene solution adds mo lecular oxygen reversibly if X is chlorine and irreversibly if X is iodine. The crystal structure of the complex IrIO(2)(CO)[P(C(6)H(5))(3)](2) * CH(2)Cl(2) is reported here and compared with a previous study of the structure of IrClO(2)(CO)[P(C(6)H(5))(3)](2). The O-O bond length is 1.47 +/- 0.02 angstroms in the irreversibly oxygenated iodo-compound and 1.30 +/- 0.03 angstroms in the reversibly oxygenated chloro compound.     

Human prion protein cDNA: molecular cloning, chromosomal mapping, and biological implications

A human complementary DNA whose protein product is considered to be the major component of scrapie-associated fibrils in Creutzfeldt-Jakob disease, kuru, and Gerstmann-Straussler syndrome has been identified and characterized. The extensive homology of this gene sequence to the hamster PrP 27- to 30-kilodalton prion protein complementary DNA clone, and its existence as a single copy in the human genome, leads to the conclusion that this is the human prion gene. This human prion gene has been mapped to human chromosome 20, negating a direct link between the prion protein and Down's syndrome or the amyloid of Alzheimer's disease.     

2000 年以来福州地区夏季极端高温的新特征及成因探讨

目的研究海兰褐蛋种鸡夏季适宜环境温湿度。方法在6栋有环控系统的鸡舍中,测定6—8月鸡舍的温度和湿度,记录30000羽0~26周龄海兰褐蛋种鸡的体质量、开产日龄、产蛋量、破蛋数和蛋总数,以及180000羽种鸡的孵化性能和60枚蛋的200日龄蛋品质;计算鸡舍日平均温度、湿度和温湿指数(temperature-humidity index,THI)、体质量均匀度和变异系数;分析种鸡适宜的THI范围。结果6—8月日平均温度、湿度和THI分别为22.07~30.51 ℃、61.88%~93.20%和70.70~82.46。种鸡育雏和育成期体质量及均匀度均可达标。种鸡开产日龄140 d,220日龄内平均产蛋率93.93%、破蛋率0.50%、受精率94.49%、受精蛋孵化率91.20%和受精蛋健雏率92.51%。舍内温度和THI均与产蛋率呈极显著正相关(P<0.01),湿度与产蛋率和蛋总数均呈极显著正相关(P<0.01);温度、湿度和THI均与破蛋率呈极显著负相关(P<0.01)。蛋品质分析结果显示：平均蛋质量59.21 g、蛋壳强度5.45 kg/cm²、蛋壳厚度0.39 mm、蛋形指数1.28、蛋黄颜色6.10、蛋黄比率27.78%和哈氏单位80.42。结论夏季海兰褐蛋种鸡在THI为70.70~82.46的环境下,生长发育、孵化性能和蛋品质良好。     

车载式果园静电喷雾机的研制

针对目前果园施药过程中耗时费力及环境日益恶化的问题,设计了一款轻便、高效、省药、能减少对环境的污染、悬挂于农用三轮车尾部的果园静电自动喷雾机。该喷雾机有效减小了劳动强度,降低了农药施用量,高效低污染。因此,这种新型的车载果园静电喷雾机具有良好的推广应用前景。     

纤维素基吸附材料除污工艺及吸附模型研究进展

纤维素基吸附材料因其具有原料种类丰富、来源广泛、价格低廉和可循环再生等优点,在重金属和有机废水处理领域中越来越受到广泛的关注。本文以纤维素基吸附材料为对象,重点从吸附工艺及吸附模型等方面综述了其在重金属和有机污染物去除方面的研究进展,揭示了吸附工艺、吸附模型、吸附机理、吸附性能之间的内在逻辑关系。最后,总结了纤维素基吸附材料在重金属和有机废水处理领域存在的一些问题并对其应用作出了展望。     

生物质改性吸附材料的制备工艺优化及对氨氮的吸附特性

为探究农业生物质再利用方法,以香蕉皮为原料,通过化学改性制备改性吸附剂,去除水中的氨氮。通过对比实验选择Na OH作为改性剂对香蕉皮粉末进行改性,单因素实验探讨了改性剂浓度、改性时间、原材料粒径及固液比对制备过程的影响及最佳制备工艺参数,结果表明:香蕉皮粉末粒径为100~120目,以0.2 mol·L~(-1)的Na OH水溶液作为改性剂,以10 g·L~(-1)的固液比,对香蕉皮粉末改性20 min为最佳的制备条件,在此条件下制得的改性吸附剂产率为64.83%。扫描电镜(SEM)、傅里叶变换红外光谱(FT-IR)、BET法测定比表面积及孔径分析结果显示,材料经改性后,表面孔道结构和官能团的变化有利于吸附氨氮。利用制得的材料吸附不同浓度的氨氮废水,并对实验结果进行等温拟合分析,Langmuir拟合结果表明改性香蕉皮吸附剂对水中的氨氮具有较高的吸附容量(qm=16.051 mg·g-1),优于沸石和活性炭,Freundlich拟合结果表明材料吸附氨氮属于较易发生的吸附(1/n=0.681)。研究表明,改性香蕉皮对氨氮具有较高的吸附容量,优于沸石和活性炭,对氨氮的吸附较易发生。     

煤基NaA分子筛材料的合成及其对Cd2+的吸附

为实现废弃物资源化利用,采用煤矸石为原料制备分子筛环境修复材料。通过对煤矸石（CG）的硅铝比进行调节,利用煅烧-水热晶化法分别在500℃和750℃下成功合成了NaA-500和NaA-750两种煤基NaA分子筛材料。进一步采用X射线衍射（XRD）、扫描电镜（SEM）等表征方法探讨了分子筛的结构特征和表观形貌,并对吸附过程进行吸附动力学和等温吸附线的研究分析,以深入探究其对Cd²⁺的吸附特性。结果表明：相比煤矸石,NaA-750和NaA-500对Cd²⁺的最高吸附量分别为392.9 mg·g^-1和208.9 mg·g^-1,分别是煤矸石的4.5倍和2.4倍,且NaA-750和NaA-500对Cd²⁺的吸附过程遵循准二级动力学规律。吸附等温线结果显示,NaA-500和NaA-750对Cd²⁺的吸附符合Langmuir等温吸附模型。综上所述,以煤矸石为原料制备的NaA型分子筛对Cd²⁺的吸附能力明显提升且具有较高的吸附容量,对去除废水中Cd²⁺具有潜在应用价值。     

苯多羧酸分子标志物对生物炭吸附磷行为的表征

生物炭因其具有多孔、比表面积较大、含氧官能团较为丰富且芳香性较强等优点而在农业面源污染控制方面具有良好的应用前景。然而,生物炭应用于土壤后难以从土壤颗粒中分离出来,从而制约了其对农业面源污染物吸附行为的预测。分子标志物技术在表征有机碳行为领域做出了重要的贡献,苯多羧酸（Benzene polycarboxylic acids,BPCAs）分子标志物方法的引入,可为表征生物炭与磷之间相互作用提供新的视角。因此,本研究采用批量吸附实验,考察了烟秆和松木及其制备的生物炭对磷的吸附行为。结果表明,随热解温度的升高,生物质及其生物炭中各BPCAs含量及苯六甲酸（Benzene hexacarboxylic acid,B6CA）对BPCA的贡献率随热解温度的升高而增加,生物炭的芳香缩合度不断增强;两类生物炭对磷的吸附量均随热解温度的升高而降低,其中400℃烟秆生物炭和200℃松木生物炭对磷的吸附量最大。表面含氧官能团的减少和静电排斥作用降低了生物炭对磷的吸附,而较大的比表面积使烟秆生物炭的吸附量高于松木生物炭。烟秆生物炭中B6CA含量高于松木生物炭,因此其对磷的吸附量较松木生物炭高。     

Helium on venus: implications for uranium and thorium

Helium is removed at an average rate of 10(6) atoms per square centimeter per second from Venus's atmosphere by the solar wind following ionization above the plasmapause. The surface source of helium-4 on Venus is similar to that on Earth, suggesting comparable abundances of crustal uranium and thorium.